Radio speaker unit support



April.6, 1943. E. o. DUMAS n y RADIO SPEAKER UNIT SUPPORT gmc/Wto@ Patented Apr. 6, 1943 UNITED STATES PATIENT OFFICE RADIO SPEAKER UNITASUPPORT' Ellsworth 0. Dumas, Scottville, Mich.

Application July 5, 1941, Serial No. 401,251

6 Claims.

This invention relates to the class of yrecordingand reproducing, and pertains particularly to improvements in mountings for loud speakers.

The principal object of the present invention is to provide an improved radio loud speaker mounting board or baille board by means of which baiile board and cabinet resonance is reduced to a minimum.

Another object of the invention is to provide an improved radio loud speaker support which is So designed that the air pressure upon the back of the loud speaker cone is maintained atall times at substantially the same pressure whereby there is obtained elimination of cabinet boom and hollowness or barrel effect which is so common to structures in which the reproducer unit is mounted in an ordinary wooden cabinet.

Another object of the invention is to provide a support and housing for a loud speaker unit in which the unit is enclosed within a sound absorbing chamber and in which a wall ofthe chamber is provided with an opening over which the speaker cone of the unit is secured, the said wall being of novel construction to absorb vibration and thereby reduce resonance produced noises.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing, it being understood, however, that the invention is not to be considered as limitedby the specific illustration or description but that such illustration and description constitutes a. preferred embodiment of the invention.

In the drawing:

Figure 1 shows a vertical longitudinal section through a loud speaker baille board support and housing constructed in accordance with the present invention;

Figure 2 is a fragmentary section on an enlarged scale through a portion of the center of the baffle board; and Figure 3 is a fragmentary section taken on the line 3 3 of Figure 1, and on an enlarged scale.

Referring now more particularly to the drawing, the radio loud speaker unit is indicated generally by the reference character S. This unit includes the usual frame I of open form and conical design, having at the larger end thereof the annular mounting ange II.

In accordance with the present invention the speaker unit S is enclosed within a sound absorbing box or housing H. This housing comprises a front wall or baille board H1 upon which the speaker unit is mounted as hereinafter de- Cil scribed, a back wall H2 and top, bottom and side walls designated respectively H3, H4 and H5.

f The front wall of the housing or baille board is made up in laminated form and has outer layers of veneer wood I2. The inner face of each of these veneer wood layers has placed thereagainst a sheet or layer I3 of heavy felt paper and interposed between the felt paper sheet or layer is a sheet I4 of lead preferably of 16 gauge or heavier thickness.

The several laminations making up the baille board H1 are secured together by bolts I5 which, as clearly shown in` Figure 2, do not extend entirely through the board but `secure the inner and outer veneer wood layers and felt paper to the central lead sheet. In other words, some of the bolts pass through the lead sheet inwardly through the inner paper layer and inner veneer wood board while others pass through the lead sheet `and outwardly through the outer paper layer and outer veneer wood board.

At the center of the baffle board there is formed the opening I and the annular frame portion I lof the speaker is secured to the inner side of the baffle board concentric with this opening.

The inner side of the baffle board is also covered with a relatively thick layer of rock wool or other suitable sound absorbing materal such as jute and the like. This layer of sound absorbing material which overlies the inner side of the lbaiile board is indicated by the numeral I1.

vThe top, bottom, side and back walls of the housing are also of laminated construction and are made up of an outer section or layer of wood veneer I8, the inner face of which is covered with a sheet of heavy felt paper I9. Overlying each sheet of paper I9 and thus covering each of the top, bottom, back and side walls is a sheet of lead 20 of the same weight as the lead sheet I4 which is used in the baille wall. Each of these walls is also covered with the relatively thick layer or bat of rock wool or other suitable sound absorbing material, these layers being indicated by the numeral 2'I.

Extending around the edge or periphery of the baiiie wall is a rubber shock absorbing band or strip 22 which may be secured in any suitable manner to the edge of the baffle wall and it is also secured to the adjacent edges of the top, t

bottom and side walls so that the baffle wall is integrally connected in the housing structure. The face of the baille wall is also outlined by the rubber gasket 23 which engages the inner side wall of the cabinet, not shown, in which the present speaker housing structure may be mounted.

With the present speaker housing structure the tone quality of the speaker is very greatly improved over speakers mounted in the customary manner directly to a radio cabinet wall and not having an enclosing sound absorbing casing or housing. The speaker efciency is greatly improved and the power handling ability is greatly increased.

By arranging the securing bolts in the baille wall structure in the manner shown and described there is obtained a neutralizing effect on any motion set up by the movement of the speaker cone and, therefore, there is obtained a complete elimination of baille resonance.

While the dimensions of the sheet or walls .of wood veneer and of the other materials may be varied as desired, it is preferred that the veneer be of approximately one-quarter inchthickness and that the inner wall layers of rock wool be approximately two inches thick.

By the provision of the rubber strips around the baille board, there is provided for the baille boarda floating connection with the rest of the speaker unit enclosing structure.

With this radio speakerunit support or nonresonant speaker baille the air pressure or loading of the 'speaker is kept directly on the front of the speaker cone instead of the cabinet or baille, since any motion of the speaker baille or cabinet sets up air movements that are not in accord with the movements of the yspeaker cone, and these extraneous cabinet or baille Inovements or vibrations cause serious distortion in the original reproduced speech or music. The

present type of baille eliminates this source of distortion almost entirely.

I claim:

l. A radio loud speaker support comprising a baille board of laminated constructionand having Aat least three laminations, the board having a central lamination of soit metal, said vboard having an opening over which a loud speaker cone is positioned, and a sound absorbing housing connected with one side .of the baille board and enclosing the speaker unitl 2. A radio loud speaker unit support .comprising a housing having one wall provided with an opening .and constituting a baille board, said opening being designed to have a speaker unit secured thereover upon the inner side of the board, said baille board being of laminated constructionand having at least three laminations and including a central lamination of sheet lead,

and a relatively thick layer of a fibrous sound absorbing material overlying the interior surface of the housing.

3. A radio loud speaker unit support comprising a housing, one wall of said housing constituting a baille board and having an opening over which a speaker unit may be secured, said baille board comprising a central layer of sheet lead and inner and outer layers of wood, securing members connecting said lead layer with the outer wood layer, each of said'securing members extending only from and through the lead layer toward and through one wood layer, and a rela tively thick layer of brous sound absorbing ma- Aterial.overlying'the inner surfaces of the housing.

4. A radio loud speaker unit support comprising a housing, one wall of which constitutes a baille board having a central opening over which the unit is secured, said baille wall being of laminated construction and including a central layer of sheet lead and inner and outer layers oi wood, securing elements extending from said lead` layer inwardly to andfconnected with the inner wood layer, securing elements extending from lthe Ylead layer outwardly to andsecured to the outer wood layer, .the housing having top, bottom, sideV and back walls, .a sheet of lead covering each of said last mentioned walls, and a relatively thick vlayer of fibrous ysound absorbing material covering the inner wall surfaces of the housing.

5. A 'radio Aloud speaker unit support as set forth in claim-4 -in whichsaidtop, bottom, side and back walls are exteriorly formed of wood veneer, and -a-covering over the inner faces of said last -mentioned wallsrof felt-paper which is interposed between the .wood veneer and the lead sheet.

`6. Ara'dio vloud speakerunit support comprising a laminated board havinga central opening over which the unit .-is secured, said boardcomprisingiav central lamination of sheet lead, a layer of felt paper disposed over eachface' of the lead sheet; and a' relatlve'lytliin Woo'd sheet covering eachgpap'erlayer, and aplurality of 'securing elements, certainof which arel connected with and extendrfromfth'el'eadsheet in one'dlrection therefrom 'to the 'adjacent wood layer andthe 'others of `which' extend fromand are connectedwith 4the lead islreet to and-have connection 'with' the other wood-layer. 

